Excavators Filemon Gallegos, from left, Ray Smith, and Rud Krisch clear material from a sluice gate that fed the upper labor acequia and dates from c. 1904, Wednesday, May 1, 2013, at an archaeological dig site at Brackenridge Park in San Antonio. It is thought that the sluice gate, which is part of the upper labor dam, sits atop the original Spanish colonial structure, built in 1776. (Darren Abate/For the Express-News)

Photo By Photo by Darren Abate/Express-News

UTSA project archaeologist Steve Smith shows an excavation of the original Alamo dam, Wednesday, May 1, 2013, at an archaeological dig site at Brackenridge Park in San Antonio. The dam diverted water from the San Antonio River into the Acequia Madre, which brought water to the Mission San Antonio de Valero, later known as the Alamo. (Darren Abate/For the Express-News)

Photo By Darren Abate/Darren Abate/Express-News

UTSA project archaeologist Steve Smith, left, and contractor Ray Smith, discuss an excavation of the original Alamo dam, Wednesday, May 1, 2013, at an archaeological dig site at Brackenridge Park in San Antonio. The dam diverted water from the San Antonio River into the Acequia Madre, which brought water to the Mission San Antonio de Valero, later known as the Alamo. (Darren Abate/For the Express-News)

Photo By Darren Abate/Darren Abate/Express-News

UTSA project archaeologist Steve Smith shows a map of the original Alamo dam, Wednesday, May 1, 2013, at an archaeological dig site at Brackenridge Park in San Antonio. The dam diverted water from the San Antonio River into the Acequia Madre, which brought water to the Mission San Antonio de Valero, later known as the Alamo. (Darren Abate/For the Express-News)

Irrigation features buried for almost 300 years, including portions of an early 1700s dam, have been found in the northern area of Brackenridge Park, the city, San Antonio River Authority and Witte Museum announced Thursday.

Local and state officials will provide more details Friday of recent excavations that unearthed waterway features linking the park to the Spanish colonial era in San Antonio.

City Archaeologist Kay Hindes said the discoveries, done under contract with the river authority for trailheads and other features of the Museum Reach of the San Antonio River Improvements Project, revealed “one of the most concentrated groupings of acequia features in the past 10 or 15 years.”

She called them “truly significant finds” that reveal a part of the Spanish colonial history of the park.

The acequias, or irrigation waterways, were essential lifelines for early settlers under Spanish rule.

The dam, built around 1719 during the Spanish colonial era, was part of the Acequia Madre, or Alamo Acequia, to serve the Mission San Antonio de Valero.